Hydraulic work hold-down or clamp



Sept. 11, 1951 2,567,641

M. W. HAZELTON HYDRAULIC WORK HOLD-DOWN OR CLAMP Filed July 28, 1949 v I4 FlaL ATTORN EYS.

Patented Sept. 11, 1951 UNITED STATES" PATENT OFFICE HYDRAULIC WORK HOLD-DOWN OR CLAMP yMerrill W; Hazelton,- Cincinnati, Ohio, assigner to Ihe Cincinnati Shaper Company, Cincinnati, Ohio, a corporation of Ohio Application July2'8`; 1949, Serial No. 107,249v

6 Claims.

invention relates to'a hydraulic work holddown or clamp for use with machine tools such shears or in any other machine or device where it is necessary to hold-down or clamp `Work or other objects..

Myr hydraulic hold-down is of the general type described in the Robert T. Hazelton Patent No. 1,881,185 issued October 4, 1932, but has specic advantages thereover. In a hydraulic hold-down of: the piston type, the fluid which usually consists f oil has a tendency to seep. past the piston` While this is an advantage in lubricating the walls of the cylinder, it also has'the disadvantage of permitting oil at times'to drip upon the work. ItisV an object of my invention to provide a hydraulic hold-down which has the advantage of permitting full lubrication of the piston, but prevents any of theoil which has seeped bythe piston from dropping on the work under the holddown? Y A' further object of my invention is to provide a hydraulic hold-down which is extremely longlived in that the movable parts are formed solely of metal, but which will operatelwith great rapidity and smoothness.

These and other objects of my invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these speci'- ications, I accomplish by that certain construction and arrangement of parts of whichvI shall now describe an exemplary embodiment. Reference'isnow made to the drawing whichforms a part hereof, and in which:

Figure 1 is a fragmentary front elevation with a? portion broken away showing two of my novel hydraulic hold-downs.

Figure 2 is a cross section of one of my hydraulicr hold dow-ns with the hold-down in its raised position. y

Figure 3 is across section of one of my hydraulichold-downs similar to Figure 2 but with the hold-down foot in lowered or operative" position.

Figure 4 is a cross section of. the piston used in my hydraulic hold down.

Briefly, in the practice of my invention, I provide a hydraulically operated hold down having a metallic piston carrying rings reciprocated in a cylinder. Within the cylinder and below the travel of the piston, I provide a well which catches the oil which has seeped around the piston. This well has an outlet port which is connected to a suction line and which removes the accumulated oil from the well.

the piston'itself', which is composed of three discs' f ner ring and.v with the slots of the three rings staggered so as to provide the tightlyV sealed piston.v

Referring'to the drawing, the piston I- of myl hold-down rides in the vertically mounted cylinderand has a' piston rod- 3 which projects from the lower edge 4 of the' piston 2 and carriesahold-downfoot 5.

The piston I itself is composed of three discsG,v 1, and 8 held together `by a' bolt 9 and a nut IU.

rIhe innermost disc 'I has groovesl II rabbeted' out on its edges to accommodate the pistonrings I2, I3,` and I4. These rings are slipped into placevv asy shown in Figure 4 before the three discsv 6, 1, and 8 are assembled togethen the piston rings I2, I3, and I4 need not be sprung apart to slide over the piston, but are merelyfir'rserted into place. The piston ring I2 is beneath the piston rings I3 and I4 and the slots of all three rings are staggered in reference to eachVV othe'rto provide agood, permanent seal. Within the cylinder 2 andispaced from the walls there'- of, I providea tube I5 whichv at its bottom edge`v I6 is tightly fastened tothe mner'-wa1l of the cylinder 2. The tube `I5 surrounds the piston rody 3' and forms )a well I1 between the cylinder wall 2 andthe tube I5.

On the lower face of the piston I, I provide a1 I 'provide a piston return springy 20 which issea-ted on the Well bottom II with the top of the spring against the lower edge I9 of the skirt I8.

The hold-down foot 5 is of greater diameter thanv the internal diameter of the cylinder 2 and hence limits the upward movement of the piston I.

The hydraulic hold-down is actuated by a mechanism in the shear and operates by fluid under pressure entering the chamber 2I in the cylinder 2 above the piston I and hence forcing the piston together with its piston rod and holddown foot 5 downwardly as shown in Figure 3. When this pressure is removed by mechanism in the shear, the return spring 20 forces the piston and its attenuating fixtures upwardly by pressing on the lower edge I9 of the skirt I8.

When oil seeps from the chamber 2| past the Another feature of my hydraulic hold-down is u piston I, it is restricted to a. space against the By this means;

inner wall of the cylinder 2 by the skirt I8 and directed to the interior of the Well I1. An outlet port 22 is provided in the well I'I and a connection 23 is made between the port 22 and a suction line 24. The suction line 24 is connected to a suction pump and the oil recovered from the well l1 is discharged into an oil sump. From the above it is apparent that I have provided a hydraulic hold-down having a metallic piston operated hold-down foot and which is provided with means for preventing oil which seeps past the piston from ilowing on the work. I have also provided a very tight and wearable piston which may be easily assembled without the necessity of springing apart any piston rings.

While in the above description and drawing I have described land shown a hydraulic hold-down for use on a power shear, it is to be understood that I do not intend to limit my hold-down for this specific purpose since my hydraulic holddown may be used with other machine tools on other devices where material or work must be held down or clamped.

Modifications may be made in my exemplary structure without departing from the spirit of my invention. Having thus described my invention in an exemplary embodiment, what I claim as new and desire to secure by Letters Patent is:

l. In a hydraulic hold-down, a hydraulically operated piston mounted in a vertical cylinder and having a piston rod projecting from the lower end of said cylinder and carrying a hold-down foot, a tube surrounding a portion of said piston rod and spaced from the interior `wall of said cylinder, a fluid tight seal between the lower edge of said tube and said cylinder wall so as to provide a well between the tube and cylinder wall, and an outlet port adjacent the bottom of said well, said piston having a downwardly projecting skirt the lower edge of which is at all times within the well.

2. I n a hydraulic hold-down, a hydraulically operated piston mounted in a vertical cylinder and having a piston rod projecting from the lower end of said cylinder and carrying a hold-down foot, a tube surrounding a portion of said piston rod and spaced from the interior wall of said cylinder, a iiuid tight seal between the lower edge of said tube and said cylinder wall so as to provide a well between the tube and cylinder wall, and an outlet port adjacent the bottom of said well, said piston having a downwardly projecting skirt the lower edge of which is at all times within the Iwell, and a piston return spring within the well and operatively positioned between the well bottom and the lower skirt edge.

3. In a hydraulic hold-down, a hydraulically operated piston mounted in a vertical cylinder and having a piston rod projecting from the lower end of said cylinder and carrying a holddown foot, a tube surrounding a portion of said piston rod and spaced from the interior wall of said cylinder, a uid tight seal between the lower edge of said tube and said cylinder wall so as to provide a well between the tube and cylinder' wall, and an outlet port adjacent the bottom of said well, said piston having a downwardly projecting annular skirt spaced from the interior' wall of the cylinder and with its lower edge at all times within the well.

4. In a hydraulic hold-down a hydraulically operated piston mounted in a cylinder and having a piston rod carrying a hold-down foot, a) well provided within the cylinder beyond thef piston path and on the low pressure side of thel piston and an outlet port in said well to permit removal of fluid seeping past the piston, said outlet port being connected to a suction line, and fluid directing means incorporated in said piston for directing seeped iluid to said well.

5. In a hydraulic hold-down a hydraulically operated piston mounted in a cylinder and having a piston rod carrying a hold-down foot, a

well provided within the cylinder beyond thev piston path and on the low pressure side of the piston and an outlet port in said well to permit removal of fluid seeping past the piston, and uid directing means incorporated in said piston for directing seeping fluid to said well.

6. In a hydraulic hold-down a hydraulically operated piston mounted in a vertical cylinder and having a piston rod projecting from the lower end of said cylinder and carrying a holddown foot, a well provided within the cylinder below the piston path in the low pressure side of the cylinder, an outlet port in said well to permit removal of uid seeping past the piston, said piston having a downwardly projecting skirt spaced from the cylinder wall and from the piston rod for directing seeping fluid to said Well.

MERRILL W. HAZELTON.'

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,728,591 Brauer Sept. 17, 1929 1,751,350 Moyer et al Mar. 18, 1930 2,003,769 Christenson June 4, 1935 2,145,384 Allin Jan. 31, 1939 2,355,721 Foutz Aug. 15, 1944 2,374,011 Gunderson Apr. 17, 1945 2,394,364 Christensen Feb. 5, 1946 2,442,057 Page May 25, 1948 2,464,710 Patterson Mar. 15, 1949 2,514,016 Valbuena Casado July 4, 1950 FOREIGN PATENTS Number Country Date 411,193 Great Britain June 7. 1934 

